TF. Topic 1/ — Eurojjean Geological Surveys. 451 



The field work is done on various scales, from 1 : 5,000 to 

 1 : 25,000 ; the publication is usually on the scale of 1 : 100,000, but 

 in special cases 1 : 50,000. 



Two meridians are used on the maps — Ferro (18° 9' W. of 

 Greenwich) and Munich (11° 36' E. of Greenwich). The maps are 

 not contoured. 



Explanations of separate sheets are not published, but the maps 

 are gi'ouped, for purposes of explanation, as follows : — 



1. ' Geognostische Beschreibung des Bayerischen Alpengebirgs und 

 seines Vorlandes' (southern frontier), 5 maps. 96 marks. 



2. ' Geog. Besch. des Ostbayerischen Greuzgebirgs ' (Bayreuth, 

 Eatisbon, Passau), 5 maps. 108 marks. 



3. 'Geog. Besch. des Fichtelgebirgs und Frankenwaldes' (N. of 

 Bayreuth), 2 maps. 70 marks. 



There is no official general map ; but the director has published 

 the following, without text : — ' Geog. Uebersichts-Karte des Konig- 

 reichs Bayern,' Munich, 1858, 1 : 500,000. Price 17-20 marks. 



Belgium. — Service de la Carte Geologique cle la Belgique (Brussels). 



This survey was established in 1877, as a part of the ' Musee 

 Eoyal d'Histoire Naturelle de Belgique' (Brussels). The work is 

 executed under the ' Commission de Controle de la Carte Geologique 

 de la Belgique,' composed of five members of the Royal Academy of 

 Belgium, with M. Stas as president. The surveying work is done 

 under the direction of Ed. Dupont, with three ' conservateurs ' and 

 eleven assistants, A peculiar feature of this survey is that each 

 main division of the geological series is traced out completely by one 

 man, so that an index map of progress is also a geological index map. 



The map is on the scale of 1 : 20,000, with contours at 5 metres 

 interval on the left bank of the Mouse, and at 10 metres on the right 

 bank. The map is in 72 main divisions ; each containing, when 

 complete, 8 sheets ; in all there will be 450 sheets. The meridian 

 is Brussels, 4° 22' E. of Greenwich. Each sheet is accompanied by 

 ' Texte explicatif ' (see below, ' Annales'). 



The maps give the nature of the soil, and note by dark shades of 

 colour, the actual areas at which solid rock is exposed. 



The memoirs issued by the Survey are in two forms, dating from 

 1877 : — ' Annales du Musee R. d'hist. Nat. de Belgique,' in fob, each 

 volume with atlas ; and ' Bulletin,' in 8vo. The former is divided 

 into four series — palaeontology, lithology, stratigraphy, existing 

 fauna. The stratigraphical series is in explanation of the sheets of 

 the map. 



A general map — ' Carte Geologique de la Belgique, exeoutee par 

 ordre du Gouvernement,' scale 1 : 160,000 — was prepared by Andre 

 Dumont from 1836 to 1854, and was published in 1854. A new 

 issue of this was made in 1877, in two editions — soil and rock, price 

 40 francs each map. This map was accompanied by Memoirs. 

 Those on the ' Terrain ardennais et rhenan ' were published by 

 Dumont in the Mem. Acad. Boy. Belgique, 1847 and 1848 ; those on 

 the 'Terrains cretaces et tertiaires,' prepared by Dumont and edited 

 by M. Mourlon, are published in four vols. 8vo. 1878-1882. 



